Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
thuc van » thuc vat, thuc dan, thuc va
van hanh » van thanh, ban hanh, van anh
hanh doi » thanh doi, hanh noi, hang doi
so sach » so sanh, bo sach, co sach
mang xa » lang xa, mang may, dang xay
hieu ve » hieu va, hieu van
doi cua » dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
sach v » sach va, sach y, sach 2
ve cam » ve cham, ve cac, va cam

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: so sach v ((mang xa) or (nang x)) hoi. hieu ve cam thuc van hanh doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach v ((mang xa) OR (nang x)) hoi. hieu ve cam thuc van hanh doi cua tre.
• Adding a wildcard symbol may retrieve word variants: so sach v ((mang xa) or (nang x)) hoi. hieu ve cam thuc van hanh doi cua tre*.